Transmission is a BitTorrent client for the Mac and Linux operating systems. It is the most popular client on Mac OS X and the default BitTorrent client on many Unix and Linux distributions, including Ubuntu, Mandriva, Fedora and OpenSuse. Although open source and technically cross-platform in nature, the developers of Transmission have not released a Windows version of the software yet.

Transmission-Qt Win is an unofficial Windows build of Transmission which features a simple interface on top of the cross-platform back-end. The interface and functions of the Windows port is identical to that found on the Mac and Linux counterpart. Transmission is a pretty advanced BitTorrent client with powerful features, most of these already available on uTorrent and similar software with the exception of blocking bad peers with a blacklist.